Rare weather event produces spontaneous snowballs This Jan. 30, 2016 photo provided by The Nature Conservancy shows a rare weather event that caused spontaneous snowballs at The Nature Conservancy’s Silver Creek Preserve and surrounding fields near the tiny town of Picabo, Idaho. (Sunny Healey/The Nature Conservancy via AP)
Rare weather event produces spontaneous snowballs
Lexile

Thousands of snowballs rolled in a flat central Idaho field look like the work of hundreds of ambitious kids, except there are no human tracks.
 
A rare weather event caused the spontaneous snowballs at the Nature Conservancy's Silver Creek Preserve and surrounding fields near the tiny town of Picabo.
 
Preserve manager Sunny Healey spotted the cylindrical shapes up to 18 inches high on Jan. 30 following an overnight windstorm and how they created long lines in the snow as they moved.
 
"You could see the tracks that they made, and I thought that was really curious," Healey said. "I had to stop a couple times. Then, along Highway 20, there were thousands of them."
 
So-called snow rollers are so rare and fleeting that the precise weather conditions needed to form them are not defined, said Jay Breidenbach, a meteorologist with the National Weather Service. Snow rollers up to 18 inches are especially rare.
 
"Those are some pretty big rollers," Breidenbach said. "I've seen some small rollers, but never that big."
 
In general, it takes an unusual combination of a couple of inches of snow with the right water density and temperatures near freezing, followed by strong winds, he said.
 
"It can't be real dry snow or it would blow into drifts," Breidenbach said.
 
Rollers require some type of firmer base, such as a frozen layer of earlier snow, for the new powder to start rolling on. Plus, the wind must be strong and steady but not with powerful gusts that could damage the formations.
 
"It would probably blow them apart because they are fragile," Breidenbach said.
 
It snowed on Jan. 29, with the snow becoming wetter toward evening, said Healey, who lives at the preserve and noted that winds woke her up.
 
In her five years working at the preserve, she had never seen such an event, but a local rancher in his 70s told her he's spotted them twice in previous decades.
 
"We know basically how they form and why they form, but we don't know the exact details," Breidenbach said. "It would be interesting to go there with some weather instruments to watch them form."

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CRITICAL THINKING QUESTION
How did wind create the snowballs?
Write your answers in the comments section below


COMMENTS (5)
  • ericksone1-gau
    2/25/2016 - 02:28 p.m.

    I think that kids made tiny snowballs and then leave them there and then when high winds blow the snowballs can't stick to the slippery ice beneath and just start rolling getting bigger and bigger until the wind dies down.

  • maiacariadus-sch
    3/01/2016 - 03:19 p.m.

    6)This story interests me because wind doesn't just make snowballs everyday.The snow has to be wet and the wind has to be just right.If the wind is too violent,the snowballs would break apart.If the wind is too light,snowballs would not form.

  • mackenzieg11-col
    3/02/2016 - 06:57 p.m.

    How did the wind create the snowballs? This is my proposal as the article said "The wind has to be strong and steady but not with powerful gusts that would damage the formations." So the wind had to probably be blowing at atlas 30 mph and staying that way with no gusts and not stopping allowing the snow flakes to bunch up and roll along the snow creating the snowballs. Along with that there has to be another layer of frozen snow under neath for the wetter snow to roll across.

  • TaylorSeifert-Ste
    3/06/2016 - 12:40 a.m.

    This is awesome. Seeing these nature-made snowballs would be so cool. It just proves that nature is beautiful

  • markn1-pay
    3/28/2016 - 09:16 a.m.

    To create those snowballs the weather conditions had to be perfect to construct them on it's own, especially the large ones. It is a very interesting event but i do wonder if nature created a perfect snowball?

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